The present invention generally relates to surgical devices and components thereof. The invention particularly relates to vaporization electrodes adapted to vaporize biological tissue, for example, when treating benign prostatic hyperplasia by vaporizing prostate tissue in the afflicted urinary tract.
Benign prostatic hyperplasia (BPH), commonly known as enlarged prostate, is an increase in size of the prostate. BPH involves hyperplasia, an increase in the number of cells, rather than hypertrophy, an increase in cell size. If untreated, BPH can lead to partial or complete urinary tract obstruction, resulting in symptoms such as urinary frequency, urgency, or incontinence. Though not a form, precursor, or risk factor of cancer, BPH can lead to conditions such as urinary tract infection, retention, or insomnia. BPH affects about 6% of the world's males, and the risk of developing BPH increases greatly with increasing age.
The treatment of BPH can involve medication to combat both the urinary blockage as well as prostate enlargement, and involve minimally invasive therapies such as radiological operations. If these treatments fail, surgery may be performed. The most established minimally-invasive procedure is transurethral resection of the prostate (TURP), which involves removing part of the prostate through the urethra. TURP typically entails the use of surgical cutting loops or lasers to reshape and remove unwanted prostate tissue. An example is an electrosurgical probe disclosed in U.S. Pat. No. 8,167,878, whose entire contents are incorporated herein by reference. TURP procedures typically involve direct contact between a surgical instrument and prostate tissue, and may entail high operating temperatures.
Currently, vaporization treatments are viable alternatives that provide bloodless tissue ablation for patients with BPH. Vaporization treatments, such as transurethral vaporization of the prostate (TUVP), use plasma energy at relatively lower temperatures to remove tissue without directly contacting the tissue and while minimizing damage to surrounding healthy tissue. Vaporization treatments are conducted in an electrically conductive solution (e.g., saline), and utilize an instrument equipped with a vaporization electrode having a functional surface that is moved relative to the surface of tissue to vaporize the tissue. Current from the electrode's functional surface passes through the conductive solution to an associated return electrode (pole), which may be positioned in close proximity to the vaporization electrode (for example, mounted on the same instrument) or externally attached to a suitable location on the patient's body. Plasma is built up by the current flowing from the vaporization electrode through the conductive solution, and particularly over and around the functional surface of the vaporization electrode, such that the tissue is heated by the plasma and vaporized without the necessity of being directly contacted by the vaporization electrode.
Currently, vaporization electrodes exist having an electrode head having a smooth, spherical or semispherical shape on a functional surface disposed on one side of the electrode head, and a planar surface on the opposite side where feed conductors are connected to the electrode head. Because the plasma forms over and around the functional surface, the smooth, semispherical shape of the functional surface produces a semispherical vaporization effect on the tissue. The semispherical shape may facilitate producing a smooth current path back to the return electrode. However, a semispherical shape may also limit the ability to remove the intended tissue in an efficient, effective manner. As such, it would be advantageous to provide vaporization electrodes capable of vaporizing tissue without sacrificing smooth electrode current connection.